21/03/2005 - Concrete
reinforcements have been given the boot by
the Environment Agency which has turned back
the clock to a centuries-old process of stopping
river banks eroding.
‘Spiling’, which uses woven lengths of live
willow, is being used again by the Agency’s
workforce on part of the River Plym on the
outskirts of Plymouth.
The bank is on a Plymouth City Council-owned
piece of land which had been eroded by the
fast-flowing water.
"This is a traditional way of protecting
river banks from erosion – we call it ‘soft
engineering’. Concrete or block stone has
been used in recent decades, and while it
is very effective at halting erosion, it can
create problems because the water bounces
off it and then may erode other areas,"
Said Jess Thomasson for the Environment Agency.
"Willow takes root and grows easily.
There are two main techniques we use. The
first is using willow faggots which are bundles
of live willow staked into the ground which
then grow into clumps of trees. Spiling involves
staking live willow stumps at regular intervals
and then weaving strips of willow through
them. We decided spiling would be the best
technique for this area of the River Plym
because we have seen how well it has worked
in other locations."
The Environment Agency in Devon and Cornwall
has for a number of years been promoting the
use of willows in various forms to combat
the erosion of riverbanks. In the Cornwall
area there are six sites where willow has
been used and is being monitored to gauge
its success.
The willow was harvested from the nearby
Plymouth City Council-owned Efford Marsh Local
Nature Reserve. The work has had the added
benefit of coppicing an area of willow and
opening up the area to more daylight. The
re-growth will not only produce straighter
willow shoots for future spiling works but
also provides an excellent habitat for birds.
